MAC - Media Access Control
Lower of the two sublayers of the data link layer defined by the IEEE. The MAC sublayer handles access to shared media, such as whether token passing or contention will be used.

MAC Address
Media Access Control address (also hardware or physical address). Every device on the Local Area Network has an unique MAC address. It is used to identify devices and to control access to the network using MAC protocol.

Machine
A networked computer dedicated to providing a certain kind of service. Usually refers to a computer that stores the website files and has a web server running on it.

Mail Relay
The process of sending a message from one point to another through an intermediary. Any mail server that supports this should have some kind of filter system in place to avoid unauthorized use by spammers. Mail servers without this protection are open to hijacking.

Mailing List
A way of having a group discussion with list subscribers by email. Emails are sent to all list subscribers. Popular mailing list programs, like Listserv and Majordomo, allow for automated subscription and un-subscription from a mailing list. Some hosting plans allow creation of mailing lists.

Mailserver
The Internet host (together with the appropriate software) that is used to send, receive and forward email messages.

Mainframe Computer
A powerful computer used for computing-intensive tasks.

Managed Web Hosting
A dedicated server that is accompanied by a full suite of technical support, maintenance and monitoring services. This differs from dedicated Web hosting, where customers are provided with their own servers but are still responsible for virtually all administrative and maintenance duties.

Masking
When viewing a website - masking is when you visit the url and the url in the address bar stays the same no matter what page on that site you visit. It is a domain that has been pointed to a different site, but you can't tell by the browser.

Master Server
Same as primary server.

Mbps - Megabits per second
Megabits (Mb) per second 1Mb = 1048576 bits

Megabyte (MB)
1MB = 1024 KiloBytes = 1048576 bytes

Memory
In a web server - the amount of RAM in your server/box is the memory. More memory equals a faster load time.

Merchant account
An account that allows you to accecpt credit cards. On a web site - this must have an integrated or third party payment gateway to be functional.

Meta tags
Tags that are hidden from the user, but utilized by search engines to determine the topic of a web page. The most common are the meta-description and meta-keyword tags.

MHz
MegaHertz = 1.000.000 Hertz

Microsoft Access
Microsoft's popular database creation and maintenance software. It is most widely used among developers who maintain online databases with Windows NT servers.

Microsoft FoxPro
Microsoft's RAD tool for creating relational databases. FoxPro is a part of Microsoft's Visual Studio. Here is the official MS FoxPro site.

Microsoft SQL Server
Microsoft's high-end SQL database running on Windows systems. Here is the official Microsoft SQL Server site.

MIDI
Older file type used to present music on the web. Usually sounded like music in a tin can.

MIME - Multipurpose Internet Mail Extensions
Multipurpose Internet Mail Extension, a standard system for identifying the type of data contained in a file based on its extension. MIME is an Internet protocol that allows you to send binary files across the Internet as attachments to e-mail messages. This includes graphics, photos, sound and video files, and formatted text documents.

Minimum Field
Seventh field in an SOA Record. The default TTL for every record in the zone. Can be overridden for any particular record. Typical values range from eight hours to four days. When changes are being made to a zone, often set at ten minutes or less.

Mirror Sites
A mirror site is an exact copy of another FTP or Web site. These are used to offset/spread traffic load on busy Web sites.

Miva Empressa
Miva's XML based server-side scripting language. Available for multiple platforms. Here is Miva Empressa home page.

Miva Merchant
Browser-based storefront development and management system for merchants. Here is Miva Merchant home page.

Mod-rewrite
An apache function that changes the way you can present pages to end users.

Modem
MOdulator-DEModulator. A device used to transform digital data sent by a computer to analog format suitable for transmission over a telephone line. It also transforms analog signals back to the digital form. A modem is required for the dial up connection to the Internet.

Money back guarantee
Common in web hosting. If you get into their control panel and don't like it or if the service is not satisfactory within a specified amount of time you can get your money back.

Monitoring
When you run an application to check on your web sites to make sure they are working. There are companies on the web that have software where they can check a page multiple times per hour.

Mosaic
A graphical browser for the World Wide Web that supports hypermedia. The NCSA (National SuperComputer Association) invented the Mosaic browser, which quickly became the industry standard. Netscape Communications Corporation later invented the Netscape Navigator, which has redefined the content on the Web. Other major companies entered the browser market with little success, until Microsoft launched their Internet Explorer which now contends with Navigator as the browser of choice. The term Mosaic is sometimes used incorrectly as a synonym for the World Wide Web.

mov (.mov)
File name extension for files with video sequences. A QuickTime player is needed in order to play such a file.

Mozilla
The original name for the Netscape Navigator browser, which is supposedly a hybrid of the words "Mosaic" and "Godzilla." Web lore has it that Mozilla means "the beast (Godzilla) that ate Mozaic (the browser)."

MP3
An extremely popular lossy audio compression format. Widely used over the Internet.

mpg (.mpg) or .mpeg
Filename extension for files in MPEG format.

mSQL (Mini SQL)
Light-weight relational database. Here is mSQL home page.

Multi-sites
Some web hosting companies allow multiple websites or domains to be hosted on an account.

Multicast
A message that is sent to a specific group of hosts.

MX Record
Mail Exchange Records create a mail route for a domain name. A domain name can have multiple mail routes, each assigned a priority number. The mail route with the lowest number identifies the server responsible for the domain. Other mail servers listed will be used as backups.

MySQL
Most popular open-source relational database. Many Unix-based plans allow MySQL databases. Here is MySQL home page.